1. Field of the Invention
The present invention relates to a method and an arrangement for applying elastic elements to an elongated, moving web of material. The method and the arrangement are particularly intended for application when mounting leg elastic on diapers, incontinence guards and like absorbent articles.
2. Discussion of Related Art
When manufacturing such articles, they are often provided with elastic threads or bands in those parts which extend around the wearer's thighs when worn, so as to increase safety against leakage and to improve shape conformity to the wearer's thighs. In order for such leg elastic to extend around the thighs of the wearer of a modern pants-type diaper, it is necessary for the leg elastic to follow the outer contours of the diaper. One method of achieving this is known from Applicant's International Application WO 89/09550, according to which elastic threads are laid-out in curves, by guiding the threads in peripheral grooves of varying axial amplitude on a rotating roller. This method, however, can only be applied for mounting leg elastic essentially in the direction of movement of an underlying material web.
Applicant's International Patent Application WO 90/00514 discloses a method of mounting leg elastic transversely to the movement direction of an underlying material web, in which elastic threads are laid around thread holding elements by a rotating thread laying-out device, said elements moving at the same speed as an underlying material web, whereafter the threads are brought into contact with the web and fastened thereto. This method is primarily suitable for producing different patterns of elastic threads in which the threads extend linearly between the longitudinally extending edges of the material web. An intricate pattern of thread holding elements is required when wishing to mount the elastic threads in a curved shape, for instance so as to follow the outer contours of a diaper of hourglass shape.